U.S. Air Force Seeks Medium Caliber Air Defense Guns to Protect Bases From Drones and Missiles.

The U.S. Air Force is seeking an organic medium-caliber gun air defense system to protect overseas air bases from drones and subsonic cruise missiles, adding a lower-cost defensive layer around critical facilities. The requirement is intended to preserve high-end interceptors for priority threats while improving resilience against sustained and saturation attacks.

The service wants a lightweight modular system able to detect, track, and engage Group 1 through 5 unmanned aircraft and cruise missiles with affordable ammunition, with performance assessed through engagement range, altitude, salvo probability of kill, magazine depth, sensors, interoperability, and deployability. Potential solutions range from Rheinmetall’s 35 mm Skyranger 35 and Skynex to Northrop Grumman’s 50 mm Raid Hunter, the 30 mm Skyranger 30, and BAE Systems Bofors’ 40 mm TRIDON Mk2, reflecting a broader effort to strengthen the inner layer of air base defense and assign lower-cost effectors to suitable targets while retaining missile systems for higher-priority threats.

Related News: American Rheinmetall presents Skyranger 762 air defense system on ISV-C at AUSA 2025

 Rheinmetall Skyranger 35 air defense system. Gun-based systems in this category illustrate the type of capability that could address the U.S. Air Force requirement. Picture source: Rheinmetall) 

The requirement concerns a Ground-Based Medium-Caliber Gun Weapon System capable of detecting, tracking, and engaging aerial threats in a contested environment. No specific caliber has been imposed. US Army definitions for medium-caliber ammunition include 20 mm, 25 mm, 30 x 113 mm, 30 x 173 mm and 40 mm rounds. Evaluation criteria include salvo probability of kill, slant range, engagement altitude, magazine depth, sensors, interoperability, mobility, and ammunition cost.

On September 3, 2026, the Air Force Life Cycle Management Center, through its C3BM Directorate at Wright-Patterson Air Force Base in Ohio, published a Sources Sought notice for the Ground-Based Medium-Caliber Gun Weapon System. The document, described in its text as a Request for Information, states that the effort is a market survey rather than a formal solicitation, with responses due by October 9, 2026. The Air Force is seeking affordable ammunition and a persistent defensive capability against subsonic cruise missiles and Group 1 through 5 unmanned aircraft, using a lightweight, modular system that can be rapidly deployed to austere locations.

Among the systems that could fit this profile are Rheinmetall’s Skyranger 35 and Northrop Grumman’s Raid Hunter. Skyranger 35 uses a 35 x 228 mm KDG 35/1000 revolver cannon with a rate of fire of up to 1,000 rounds per minute, an effective range of about 4,000 meters and programmable AHEAD ammunition. Raid Hunter follows a different approach built around a 50 mm Bushmaster Chain Gun, guided ammunition capable of in-flight correction and a networked, interoperable system controller. Northrop Grumman is planning palletized configurations followed by vehicle-mounted variants, with an architecture designed for transport aboard C-130 aircraft.

Other systems could also fall within the scope of the market survey, although no participation has been confirmed. Rheinmetall’s Skynex combines Oerlikon Revolver Gun Mk3 35 mm cannons, a rate of fire of 1,000 rounds per minute, and an engagement range of up to 4 km within an architecture that separates air surveillance from the effectors, a configuration suited to air base defense. Skyranger 30 uses a 30 x 173 mm KCE cannon with an effective range of roughly 3,000 meters, a 360-degree search radar, electro-optical sensors, and airburst ammunition. BAE Systems Bofors’ TRIDON Mk2 is another possible option, using a truck-mounted 40 mm cannon with a stated range of up to 12 km depending on target type, ammunition, sensors, and terrain. For the close-range counter-UAS segment, EOS Slinger combines a 30 x 113 mm M230LF cannon, a compact Echodyne AESA radar, and proximity-fuzed ammunition, although its ability to engage cruise missiles would still need to be demonstrated against the Air Force requirement.

The gun system would complement rather than replace Patriot, NASAMS, or other missile-based layers. Its role would be to engage drones and selected cruise missile threats at short range, provide another opportunity to destroy targets that penetrate outer defenses, and preserve more expensive interceptors for higher-priority threats. Combining radar, electro-optical sensors, and data links would also support faster assignment of each track to the most appropriate effector. This approach reduces the risk of using high-value interceptors against low-cost targets while improving defensive endurance during prolonged or saturation attacks involving several successive layers.

The requirement also reflects lessons first reinforced by the war in Ukraine, where repeated attacks involving one-way attack drones and missiles have renewed attention on gun-based air defense, programmable ammunition and the need to preserve missile interceptor inventories. More recent developments involving Iran have given the issue a direct US operational dimension, with Iranian forces employing drones and missiles against facilities hosting American personnel in the Middle East in 2026. For Washington, the issue therefore extends beyond the selection of a new gun system. It concerns the organization of a layered defense in which sensors classify and prioritize tracks, lower-cost effectors are assigned to threats within their engagement envelopes, and high-end missiles remain available for the most dangerous targets. Such an architecture provides additional opportunities for interception, improves resilience against saturation, and supports continued air base operations under attack. It could also influence future base protection concepts adopted by US allies in Europe, the Gulf and the Indo-Pacific.

Written By Erwan Halna du Fretay - Defense Analyst, Army Recognition Group
Erwan Halna du Fretay holds a Master’s degree in International Relations and has experience studying conflicts and global arms transfers. His research interests lie in Security and strategic studies, particularly the dynamics of the defense industry, the evolution of military technologies, and the strategic transformation of armed forces.